.flex__container {
  display: flex;
  justify-content: center;
  align-items: center;

  width: 300px;
  height: 300px;
  background-color: lightgreen;
}

.flex__item {
  width: 30px;
  height: 30px;
  background-color: rgb(144, 158, 238);
  
}
/* ------------------------ */

.flex__container1 {
  display: flex; 

  width: 300px;
  height: 300px;
  background-color: lightgreen;
}

.flex__item1 {
  margin: auto;

  width: 30px;
  height: 30px;
  background-color: rgb(144, 158, 238);
}